Internal combustion engines subjected to severe service, such as certain automotive engines, frequently input a great deal of heat to the lubricating oil. It is commonly known that lubricating oil cannot function properly if it is maintained at excessive temperatures for prolonged periods of time. In response to the need to keep oil temperatures within reasonable limits, it is commonly been known to use oil coolers in conjunction with internal combustion engines. Construction of an oil cooler for an internal combustion engine requires special care inasmuch as the cooling fluid, which is commonly a water/ethylene glycol solution circulated between the engine's radiator and the cylinder block, must not be allowed to come in contact with the engine's lubricating oil. If coolant leaks into the lubricating oil, the engine's bearings may be quickly ruined because the mixture of lubricating oil and coolant provides very little lubricity. Accordingly, it is imperative that an oil cooler have structural integrity such that intermixing of the engine coolant and lubricating oil will not occur. It is known to use roll bonded evaporators in the refrigeration art, but automotive oil coolers are commonly made of built-up of fin and tube type units having many separate subassemblies consolidated into a single unit by means of numerous joints, all of which may leak. An oil pan having an oil cooler according to the present invention provides the required structural integrity because no tube joints are included in the fluid passages within the oil pan, notwithstanding that a heat exchanger according to the present invention may have a large surface area due to many internal passages.
It is an advantage of the present invention that an oil pan may be equipped with a heat exchanger according to this invention at a reasonable cost, and without sacrificing structural integrity of the oil cooler.